During the first half of 1912, she patrolled Cuban waters and was at Guantanamo Bay Naval Base in Cuba from 7 to 22 June 1912 to support the suppression of an insurrection on the island.

In May 1917, he transferred to the destroyer USS Wilkes,[1] which escorted an American troop convoy from New York City to Saint Nazaire, France, in June 1917, then took up duties from July 1917 defending Allied shipping during the Atlantic U-boat campaign of World War I from a base at Queenstown, Ireland.

[3] DeLany returned to the United States in August 1918 and assumed duty as executive officer of the destroyer USS Craven upon her commissioning on 19 October 1918.

[1] DeLany left the recruiting station in November 1921, when he reported aboard the newly commissioned transport USS Argonne (AP-4) for duty as her navigator and first lieutenant.

He had duty in the Training Division of the Bureau of Navigation at the United States Department of the Navy in Washington, D.C., from October 1924 until January 1927, and for three years thereafter served as first lieutenant aboard the battleship USS Oklahoma (BB-37).

Naval Academy for the year's midshipman cruise, and carried the midshipmen through the Panama Canal to San Francisco, California, before the making the return journey with stops in the Caribbean.

[6] DeLany returned to the Department of the Navy in February 1930 and served for three years in the Ships’ Movements Division in the Office of the Chief of Naval Operations.

As part of the screen of the aircraft carrier USS Saratoga (CV-3), New Orleans participated in the Guadalcanal campaign[1] including the Battle of the Eastern Solomons, during his tour in command.

After the Japanese submarine I-26 torpedoed Saratoga on 31 August 1942, New Orleans was part of Saratoga′s escort as the aircraft carrier steamed to Pearl Harbor for repairs, arriving there on 21 September 1942.

[10] Promoted to rear admiral with date of rank effective 26 May 1942, DeLany was detached from New Orleans to report on 12 November 1942 as Assistant Chief of Staff (Operations), to Commander-in-Chief, United States Fleet, at U.S. Navy headquarters in Washington, D.C.[1] When the Joint Army–Navy Assessment Committee (JANAC) was created in January 1943 to assess enemy naval and merchant shipping losses during World War II, he was appointed as its chairman, a function he performed until relieved by Rear Admiral Jerauld Wright after the war.

[11] In addition, on 19 March 1943 he was redesignated Assistant Chief of Staff (Readiness), in that assignment serving as the U.S. Navy representative on the Joint Committee on New Weapons and Equipment (JNW), and was in this position when World War II ended in August 1945.

He was awarded a second Legion of Merit for "exceptionally meritorious service … from November 1942 to August 1945 … During this long period, by the exercise of great foresight, broad vision, unusual initiative, sound judgment, superior professional knowledge, and high executive ability, he directed the improvement and development of means, methods, and practices which kept the United States Fleet in a continually higher state of readiness for battle than those of the enemies and contributed in a great degree to the successful prosecution of the war.

He remained in this position when it moved to the United States Department of State′s International Cooperation Administration in 1955, serving continuously from May 1953 until March 1961, coordinating East–West strategic trade projects.

[14] As part of the series, DeLany wrote Bayly′s Navy, a short memoir of his World War I service aboard USS Wilkes at Queenstown, Ireland.